In the event of the temporary Absence or Disability of the Sheriff of Chancery or of the presenter of Signatures it shall be competent to the Lord Justice General and President of the Court of Session to appoint a properly qualified Person to act as Substitute to the Sheriff of Chancery or to the presenter of Signatures Case may be, such Person receiving from the Sheriff of Chancery or from the presenter of Signatures, as the Case may be, such Remuneration for so acting as shall be fixed by the said Lord Justice General and President of the Court of Session.